(Phys.org)—Astronomers report the detection of new eruptions in two luminous blue variables, known as R 40 and R 110, located in the Magellanic Clouds. The finding, presented December 5 in a paper published on the arXiv ...

The gas and dust in giant molecular clouds gradually come together under the influence of gravity to form stars. Precisely how this occurs, however, is incompletely understood. The mass of a star, for example, is by far the ...

A spaceborne lidar instrument that fired more laser pulses than any previous orbiting instrument has ended its operations on the International Space Station, after a successful 33-month mission to measure clouds and tiny ...

If you holler at someone across your yard, the sound travels on the bustling movement of air molecules. But over long distances your voice needs help to reach its destination—help provided by a telephone or the Internet. ...

When the Swedish Tax Agency website went down for nearly two days, thousands of people across Sweden were left frustrated. Users of Gmail, Slack, Facebook, Apple services, and other popular services also regularly experience ...

Three times further away from the sun than the Earth lies an enormous lump of metal. Around 252km in diameter, the metallic "M-class" asteroid 16 Psyche is the target of NASA's next mission to the belt of giant rocks that ...

High in the snowfields atop the Rocky Mountains in Colorado, things are not as pristine as they used to be. Dust from the desert Southwest is sailing into the Rockies in increasing quantities and settling onto the snow that ...

When NASA's Aqua satellite passed over Tropical Storm Ockhi, it measured cloud top temperatures that showed strongest storms were off the coast of southwestern India. Infrared data showed Ockhi intensifing into a typhoon.

Ash clouds emitted during the eruption of an Antarctic volcano may disrupt air traffic in the southern hemisphere, according to a study made by researchers from the Institute of Earth Sciences Jaume Almera of the CSIC (ICTJA-CSIC) ...

Cloud

A cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae. Clouds are studied in the nephology or cloud physics branch of meteorology.

On Earth the condensing substance is typically water vapor, which forms small droplets or ice crystals, typically 0.01 mm in diameter. When surrounded by billions of other droplets or crystals they become visible as clouds. Dense deep clouds exhibit a high reflectance (70% to 95%) throughout the visible range of wavelengths. They thus appear white, at least from the top. Cloud droplets tend to scatter light efficiently, so that the intensity of the solar radiation decreases with depth into the gases, hence the gray or even sometimes dark appearance at the base. Thin clouds may appear to have acquired the color of their environment or background and clouds illuminated by non-white light, such as during sunrise or sunset, may appear colored accordingly. In the near-infrared range, clouds look darker because the water that constitutes the cloud droplets strongly absorbs solar radiation at those wavelengths.